Vibrating screening apparatus having deck screens that are supported by frames are known. Generally, the frames have a taller feed end and a shorter discharge end that are joined by two sides. Material to be sized is fed onto an upper shaker screen at the feed end. Material smaller than openings in the upper shaker screen fall therethrough onto a lower vibratory screen. Fines are allowed to pass through openings in the lower vibratory screen, while coarser material is discharged from the lower vibratory screen at the discharge end of the apparatus. Generally, the shaker screens in such apparatus are vibrated by means of off balanced shaft mechanisms which are coupled to the shaker screen assembly.
While the above-described apparatus are efficient for sizing stone, gravel, and other clean aggregate material, such apparatus are inefficient when the feed material comprises a wide variety material such as that found in dumps, which would include sand, soil, rocks, leaves, paper bags, sticks, twigs, cans, bottles, tires, domestic and industrial garbage and trash, and construction site debris. The separation of such materials becomes much more difficult.
There are a number of vibratory screening apparatus that are used to screen disparate feed-type materials in which comb or finger-like members formed of rods define a series of decks over which the feed material is passed. Typically, the screening decks are arranged in a shingle array fashion, with each deck generally horizontally or slightly downwardly tilted from the horizontal and having a plurality of arrays of finger or rod-like members projecting from a transverse frame, so as to provide the desired separation.
In such finger screening devices, the finger members are often mounted so that they can vibrate independently of one another. This independent movement, when the assembly is being vibrated, allows large, heavy clumps of material and other large objects to displace one or more of the finger members and pass through the deck fingers, thereby preventing the apparatus from becoming clogged.
Examples of screening apparatus which use finger members include U.S. Pat. Nos. 5,641,071 to Read et al., 5,398,815 to Hadden, 5,322,170 to Hadden, 5,219,078 to Hadden, 3,241,671 to Brauchla, 3,221,877 to Koning, and 3,042,206 to Olender.
The finger screen devices in use today have finger member assemblies which either include rod-like finger members that are bolted or welded to a traverse support bracket or have rod-like members that are individually clamped in a support block which is in turn supported by a support bracket as depicted, for example, by Erin Screens (Portland Me.) in their Cascade.TM. system.
Finger members that are rigidly attached to support brackets by mechanical means such as bolts, clips, etc., and those which are welded to support brackets are subject to mechanical failure at their point of attachment. In addition to providing stress points at which mechanical failure of the fingers can occur, assemblies exemplified by Cascade.TM. which involve the use of individually clamped finger members are also susceptible to becoming loose during operation.
The present invention provides a deck finger assembly which is an improvement over current assemblies.